According to results recently presented at the 43rd Annual Meeting of the American Society of Hematology, evidence suggests that low-dose interferon alpha (IFNa) has similar anti-cancer activity compared to high-dose IFNa, with fewer side effects for patients with CML.
Chronic myeloid leukemia (CML), also called chronic granulocytic leukemia, is a cancer of the white blood cells. The bone marrow contains early blood-forming cells called stem cells, which grow and mature into 3 blood cell types: red blood cells, which provide oxygen to tissues; platelets, which aid in blood clotting; and white blood cells, which fight infection. In the case of CML, large numbers of young granulocytes (a type of white blood cell) do not mature, resulting in an excess accumulation of these cells. These leukemia cells then crowd the bone marrow and blood, suppressing formation and function of other blood cells normally present in these areas. In addition, the leukemia cells cannot perform their function in the body properly, leaving patients susceptible to infection.
Interferon alpha (IFNa) is a biological therapy used to stimulate the body’s own immune system to fight cancer. IFNa is a standard treatment option for patients with CML, but is associated with significant side effects. Optimal doses are still being evaluated in clinical trials, with previous results indicating that patients with CML have responded to both high-dose and low- dose IFNa.
Researchers recently conducted a clinical trial evaluating the efficacy and toxicity of low-dose IFNa versus high-dose IFNa for the treatment of CML. Patients with newly diagnosed CML were divided into two groups: one group was treated with high- dose IFNa (197 patients) and the other group was treated with low-dose IFNa (197 patients). The hematological response rates at 3, 6 and 12 months for patients treated with low-dose IFNa were 74%, 77% and 84% compared to 57%, 77% and 76% for patients treated with high-dose IFNa. Approximately one year following the initiation of therapy, treatment was stopped in 22% of patients receiving high-dose therapy and 9% of patients receiving low-dose therapy due to side effects. Also, at one year, 4% of high-dose patients and 7% of low-dose patients experienced a progression of cancer. Furthermore, the 5-year survival was 51% for the high-dose patients and 53% for the low-dose patients.
These results indicate that anti-cancer responses and 5-year survival rates were not significantly different between patients receiving high-dose or low-dose IFNa. However, patients treated with high-dose IFNa experienced significantly more side effects. Further studies are warranted to define the role of low-dose IFNa in the treatment of CML.
Patients with CML may wish to speak with their physician about the risks and benefits of participating in a clinical trial evaluating high-dose versus low-dose IFNa or other promising therapies.
(Proceedings from the 43rdAnnual Meeting of the American Society of Hematology, abstract #3034, Orlando, Florida, December, 2001)
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